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Lesson 4: Megapixels

October 7th, 2009 Andrei

Now you have an idea about the differences between point and shoot digital cameras and DSLRs and you know which one is best for you. The next step is to actually buy the camera. In the next few lessons I will explain to you a couple of very important technical aspects that are essentials in choosing the right camera from the vast number of models that exists on the market today.

In every camera’s specifications you will find the number of megapixels that it has. But what is a megapixel? A megapixel means 1 million pixels. A pixel is a single point in a graphic image. All graphic images are made up of thousands of tiny points. If your camera is 5 megapixels, it means that any pictures it takes will consist of 5 million of these pixels (on its highest quality setting). Generally, 5 megapixels is enough to print good quality 8x10s. But just because one camera has a certain amount of megapixels doesn’t mean that it will take better pictures with one with a lower amount. There are many factors which affect this, including build quality, type of camera, etc.

If you’re just planning on printing small prints of your photos, or viewing your photos on a computer, you can do this with a lower number of megapixels. But if you want to print quality 8x10s, you will need a bigger number of them. For a quality print, you’d want to start with a photography which contains at least 240 DPI (or dots per inch), 300 DPI would be even better, but 240 is enough. So, for a 4×6 print at 200 DPI, we would need an image size of 960×1440 pixels or better. For a 5×7, we would need 1200×1680, and for an 8×10 we would need 1920×2400 or greater. Now, most 5 megapixel cameras produce an image of around 2592×1944, which when printed at 240dpi comes out to a 10.8″ x 8.1″ print. So, with a 5 megapixel camera you could print 8x10s but only is you are not cropping your image.

Why isn’t more megapixels always better? Camera companies keep increasing the number of megapixels and now even some point and shoot cameras have well over 10 megapixels. But does this mean that they will take pictures of better quality than older models with lower number of megapixels? The answer is no. By continuously increasing the number of megapixels which cameras can output, the camera companies are not paying as much attention to quality as they should. Just because you are cramming more pixels into a photo doesn’t mean that the pixels are sharp enough for there to be any discernible increase in image quality. So, while your pictures may be getting larger, they might not even be sharp enough to be printed at this larger size, merely because there was an increase in pixels, but not an increase in quality. In theory, more megapixels would mean a nicer photo, but in actuality it may just mean a terrible photo composed of more dots.

Once you get past 4 megapixels or so, the resolution stops mattering as much, and optical quality comes more into play. This is why a 8 megapixel DSLR camera will take better pictures than a 10 or 12 megapixel point and shoot digital. Another fact worth mentioning is that DSLRs have larger sensors than a typical point and shoot. These larger sensors produce much less noise than their point and shoot rivals, leading to a much cleaner shot.